EXTERNAL CHARACTERS AND HABITS 99
terminal phalanges only, and the flexure lines are greatly reduced. The papillary ridges form three groups of parallel lines on the sole, and oblique or transverse lines on all the phalanges except the terminal ones, where they form loops. The back of the foot and the proximal phalanges are hairy, but the remainder is glabrous.
It is, therefore, evident that the hands and feet of the Gorilla are less adapted for an arboreal life than those of the other Apes. And it will be shown later that the internal structure of the foot is adapted for supporting purposes rather than for prehension.
Hairs.—The whole body, except the face and parts of the hands and feet, is covered with long hair of a black or rufous colour, and old animals become grizzled. Eothschild (485) points out that there is a rufous phase in all the subspecies recognized by him, so the colour of the hair exhibits dimorphism. He states, moreover, that " these rufous phases have been described respectively as distinct species or races " by other zoologists. Each hair is banded, the tip and root being grey, whilst the remainder is black.
The hairs on the scalp stream backwards towards the neck, and they form a prominent crest along the line of the sagittal suture. When the animal is enraged these hairs are strongly erected, and the crest is pulled downwards and forwards with the scalp. Two streams of hairs pass down on the side of the head and include the external ear between them. . Sometimes these hairs are so thick that the ear is concealed. On the bodv the
general direction of the hairs is downwards, but there are vortices over the clavicles and in the neighbourhood of the anterior superior iliac spines. The hairs on the